1. Field of the Invention
The present invention relates to an apparatus for receiving a voice signal and data, and a controlling method thereof, and particularly, to an apparatus for receiving voice signal and data, and controlling method thereof by which a voice call can be performed even in power failure, or disorder of central processing unit (CPU) or network.
2. Description of the Background Art
Conventional switching network dealt with a voice service mainly, however, economical efficiency and service quality are improved recently by digitizing the switching operation. And at the same time, an integrated services digital network (ISDN) of 64 Kbps which integrates a circuit switching and a packet switching is able to be served.
However, requirements of user become advanced, diverse, and personalized, therefore, information of high speed and large capacity such as moving picture is needed to be transmitted. In order to satisfy the qualities required by various services and accept all services in a single communication network, an asynchronous transfer mode (ATM) which is able to process large range of bands from a narrow band ISDN service to a broad band video service.
The ATM communication method is a switching technology in broad-band ISDN (B-ISDN), and provides various services according to different traffic characteristics and system conditions using an ATM adoption layer (AAL).
The AAL is divided into AAL1, AAL2, AAL3/4, and AAL5 according to the kinds of ATM services.
The AAL1 is a connection-oriented service requiring a predetermined bit transmitting speed, is able to control the transmission time, but has a delaying element.
The AAL2 is a connection-oriented service which does not require a predetermined transmission speed. A method for processing a corresponded layer in ATM is a method for accepting a variable bit rate requiring a real time processing in the ATM network, and the method transmits various user data carried on an ATM cell through an ATM layer connection having one visual channel/path internet protocol (IP).
The AAL3/4 is a service applied when variable speed is required for both of connection-oriented and non-connection type.
The AAL5 is a service for supplying high speed service by simplifying the function of AAL3/4. The method for processing corresponded ATM layer is for accepting connection-oriented/non-connecting upper applied user data of non-real time and of variable length in the ATM network. And the above method is suggested for packet or IP service mainly.
FIG. 1 is a conceptual view showing a location of VoDSL and a structure of AAL2 area.
A voice over digital subscribe line (VoDSL) is a technology for transmitting voice using its variations digital subscriber line (xDSL), the xDSL is able to transmit data, however, it does not support real time data transmission. Also, excessive delay is generated to make the voice phone call not be smooth.
Therefore, the VoDSL adds the AAL2 area on the basis of the ATM to perform real time voice process, and adds AAL5 area to perform the data transmission.
FIG. 2 is a block diagram showing a telephone network connected to the conventional apparatus for receiving voice signal and data.
The conventional apparatus for receiving voice signal and data comprises: a splitter 10 for dividing a signal inputted from an outer data transmission unit (not shown) into an IP data packet and a voice signal; a first telephone (TP) 30 connected to a POTS channel of the splitter 10 for receiving the voice signal divided in the splitter 10; and an integrated access device (IAD) 20 for receiving the IP data packet divided in the splitter 10, changing it to voice signal, and applying the same to a plurality of second telephones 40 connected to a data network, and for changing the voice signal inputted from the plurality of second telephones 40 into the IP data packet and outputting the same through the data network.
The operation of the conventional apparatus for receiving voice signal and data will be described as follows.
To begin with, the splitter 10 divides the data inputted through digital subscriber line (DSL) from the outer data transmission unit into a voice signal and a IP data packet, applies the IP data packet to the IAD 20, and applies the voice signal to the first telephone (TP) 30 connected to an analog POTS. Accordingly, the user receives the voice signal through the first telephone (TP) 30, and transmits the voice signal through the first telephone (TP) 30 to perform a voice telephone call.
On the other hand, the IAD 20 transforms the IP data packet applied from the splitter 10 into the voice signal, and applies to the second telephone connected to the IAD 20.
The general telephone 40 transforms the voice signal into voice to provide the user, and changes the voice inputted through the second telephone 40 by the user into the voice signal to apply the above voice signal to the IAD 20.
In addition, the IAD 20 transforms the voice signal applied from the second telephone 40 into the IP data packet, and after that, transmits the IP data packet to the outer data transmission unit as passing through the splitter 10 to perform the voice telephone call.
That is, the IAD 20 operates various chips therein to transform the IP data packet inputted from the data network into the voice signal, and applies the voice signal to the second telephone 40. In addition, the IAD 20 transforms the voice signal inputted from the second telephone 40 into the IP data packet, and applies the IP data packet to the data network to perform the voice telephone call. However, the IAD 20 does not work unless electric power is applied, and therefore, the voice telephone call is not able to be performed using the telephone connected to the data network in power failure.
Also, if a network error is generated, and an error is generated in the CPU inside the IAD, the voice telephone call using the data network is impossible.